1. Sieve the flour and baking powder together in a bowl. Whisk the margarine, sugar and salt together, until pale and fluffy. Add the egg yolks, one by one and then add the grated zest, mahlab, vanilla, milk and brandy.
2. Whisk the egg whites to a thick meringue. Fold it gently to the mixture, a little at a time, alternately with the flour, with the help of a spatula. Then add the almonds and combine everything gently.
3. Grease with margarine a 30cm baking tin and empty the mixture in. Add the traditional coin and, if you wish, sprinkle with flaked almonds. Bake at 180ºC, in a preheated oven, for approximately 55 minutes. Let it rest for 5 minutes, then, remove the cake from the tin and place it on a rack to cool. You may sieve some icing sugar on top.